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5:1Improvement through grassland management
5 Managing your grazing
Whats inthis section? Preparing or grazing
Deciding the length o the rotation
Planning or critical times osward availability
Calculating the number o eedsrom a feld
Calculating the actualorage supplied.
Objective: Tocaterforrapidchangesinswardqualityand
quantitywithaexiblegrazingapproach.
Challenge: Walkandassessswardsatleastonceaweek
Achievea10%increaseindaysof
consistentqualitypasturesupplythis
year,togetherwitha0.5tonne/cow
increaseinutilisedpastureDMintake.
Target
Increasepastureintakeby1.0tonneutilisedDM/cow.
Every Day Good Grazing
Planningaexibleapproachtoensurethe
consistentsupplyofqualityforagerequired
throughoutthegrazingseasonisonething.
Actuallymaintainingitinthefaceofrapidly
changingswardgrowthrates,pasturequality
andcowrequirementsissomethingelse.
Despitetheverybestofintentions,agoodqualityspringswardalltoooftenbecomesprogressivelyless
productiveastheseasonprogressesandtherealities
ofday-to-daymanagementpressurestaketheirtoll.
Closemonitoringofprogressthroughthegrass-
growingseasonisthekeytocopingwiththe
unpredictabilitythatcanbeassociatedwith
grazing.Italsoprovidesmuch-neededcondence
toachievemorefromgrazedgrass.
ContentsTurnoutManagement Page5:3
RotationLength Page5:9
ShortfallsandSurpluses Page5:12
FeedsperField Page5:15
PastureUtilisation Page5:16
Adjusting the grazing rotationlength is essential to keep on topo swards that can grow twiceas ast one month as the next.
5Managing
yourg
razing
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5:2 Improvement through grassland management
Action planTo increase your pasture intake by 1.0 tonne utilised DM/cow.
1. Preparing or Turnout
Makesureyourpasturesandcowsare
readyforturnoutandmanagethewhole
processcarefully(Page 5:5).
2. Maintain the Best Rotation Length
Useeldcoverstoensureyourpasture
rotationlengthmatchesgrassgrowth
throughouttheseason(Page 5:9).
3. Identiy Costly PastureImbalances Early
Assessyoureldcoveravailabilityor
pasturebalancescontinuallytoidentify
costlypotentialgrazingsurplusesorshortfallsaheadoftime(Page 5:12).
4. Address SwardSurpluses Eectively
Takeeffectiveimmediateandlonger-term
actionassoonasyourgrasslookslikebeing
surplustograzingrequirements(Page 5:13).
5. Address SwardShortalls Eectively
Takeeffectiveimmediateandlonger-term
actionassoonasyourgrasslookslikebeing
inshortsupplyforgrazing(Page 5:14).
6. Calculate Feeds per Field
Assesseacheldforthenumberoffeedsitwill
providetoensurethemosteffectivemanagement
(Page 5:15).
7. Measure Sward Utilisation
CompareactualswardDMintaketothecoveryou
allocatetomonitorutilisationefciency(Page 5:16).
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Turnout management
Atturnout,milkproductionlevelsmayriseorfall
forafewdays.Thisisonlytobeexpectedas
cowsadjusttothesubstantialchangeinvolved
inswitchingsuchamajorpartoftheirDM
intakefromconservedtofreshforage.
Itisimportanttohavethecondencetostickwiththe
grazingstrategy,evenifmilkproductiontemporarily
fallssharply.
Providedadequategrazingisavailableanyeffect
onmilkoutputwillbetransientandproduction
willreturntopreviouslevelsinafewdays.
Agradualtransitiontograzingover2-3weeksor
longer,withgrazingintakesstartingat4-5kgDM/
cow/day,minimisestheseeffectsbyenablingthe
rumenmicrobestoacclimatisetothechangeindiet.
Cowsshouldbeabletograze5kgofdry
matterinthreehoursquiteeasily.
Insomecircumstances,thegroundmaybea
littletender/softinearlyspring,soalower
stockingratewillmeanlessfeetandtimeon
anyparticularareaand,therefore,lesschance
ofdamageandpoachingofthesward.This
isbestshowninthefollowingexamples:
Example calculations or spring grazing
Case 1. Grazingcoveris2800kgDM/haandtherequiredresidualis1500kgDM/ha.Soevery
hectareofgrazinghas1300kgDMtograze.
Aherdof100cowsrequiring5kgDM/
headadayofgrazingmeansthetotal
demandis500kgDMaday.
Therequired500kgdemanddividedby1300kg
supply,willbeprovidedby0.38haaday.
Case 2. Grazingcoveris2400kgDM/haandtherequiredresidualis1500kg
DM/ha.Soeveryhectareofgrazinghas
apotential900kgDMtograze.
Aherdof100cowswithadailydemandof5kg
DM/headmeansthetotaldemandis500kgDM.
Therequired500kgdemand,dividedby900kg
supply,willbeprovidedby0.55haaday.
InCase2,cowswillbespreadoveralarger
area,reducingthepotentialtocausesoildamage
bypoaching.
Alowergrazingcoverwhencowsenterisalso
usefultore-establishagrazingwedgeaftermaking
silageorwhenallgrasscoversarethesameasa
resultofwintergrazing.Inthiscase,grazingata
coverof2200kgDM/hafortherstfewelds,then
increasingthislevelofcoveroverashortperiodto
2800kgDM/hatoregainthewedge,maybethe
bestoptiontore-establishasupplyofqualitygrazing.
Sheep on Grazing Land
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Can sheep be useul to grazing managemento grass or the dairy herd?
Pros
Sheepwillgrazealloldgrass,sospring
grazingisofhigherquality
Theykeepontopofgrassgrowthoverwinter,
socowsarenotputtograzepasturesabove
therecommended2800kgDM/ha,asmost
UKgrasswillgrowtosomeextentallwinter
Extraincome.
Cons
Springcalvingsystemsrelyonover-wintered
grassandwintergrowthforgrazinginFebruary
andMarch.Sheepwilleatthatgrass
Sheepnottakenoffgrazinglandearlyenough
willdelayturnout
Grasstakendownclosetobareearthwilldelay
springregrowth
Oncesheepareremoved,allgrazingis
generallyatthesamelowlevel,resultingin
potentialofboomandbustofgrazingsupply.
Therewillbenothingtostartwith,thenonce
grassgrowsitsallreadytograzeatthesame
timeandsomecanpotentiallygobeyondthe
optimumof2800kgDM/habythetimecows
gettoit.Thissurplusmaybesilagedbutthat
canleavetoolittleforgrazingrequirements.
So what is the answer?
Grazingsheepinwinterisunlikelytobebenecial
foragrass-basedspring-calvingsystem,butitmay
haveadvantagesforotherproducers.
Sheepwillcleanpasturesnotgrazedhardenough
inautumn.Grasscarriedoverwinterwithdead
anddecayingmaterialinthebasewillreduce
grazingpotentialinthenewseason.
Whendeadandstemmaterialarelefttheywill
preventcowsgrazingdowntotheoptimumresidual
of1500kgDM/hainearlyspring.Iftheresidualislefttoohighinspringanddeadandstemmaterial
buildupinthesward,itwillreducequality,
palatabilityandgrowthpotential.
Grasswillgrowinlateautumnandwinter,aftercows
arehoused.Whenthereissignicantwintergrowth,
grazingmaybeatorbeyondthepreferredlevelof
2800kgDM/haatturnout,makingitdifculttoget
cowstograzedowntotheoptimumresidual.
Managing grazing sheep
Theproblemsofsheepgrazingtoomuchcoveroff,
delayingspringgrowthandleavingallgrazingat
thesamelowcovercanbeavoidedbyplanning
theirremoval.
Thisisbestmanagedbywalkinggrassfrequentlyand
notlettingthesheepgrazeallthegrassatonce.
Considergivinganareasuchas20%fortherstfew
weeksbeforemovingtothenext20%andsoon.
Takingthemoffgrassatdifferenttimeswillcreatea
minigrasswedge,withtheareagrazedbysheepin
Novemberreadyforcowsbeforethatgrazedby
sheepinJanuary.
Alternatives to sheep
Analternativeistograzeheifersorfaroffdrycowson
wintergrowngrassearlyintheyeartotaketheexcessoffandthencloseitupforanearlycutofsilage.
Theirmuckshouldnotreducesilagequalitywhen
stockarenotbeingfedabrousbuffer,keeping
mucklooseandeasilydispersedbysoilmicrobes
beforecutting.
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Points to consider:
Getcowsoutearlierandinlater,donotuse
perceivedwetconditionstokeepthemin.Tracksandgatewaymanagementwillenablethis
Askwhetherthecentreoftheeldisdry
enough.Ifitis,butthegatewayislimiting
access,usemultipleentriesfromtracks
Ensureagrassresidualof1500kgDM/ha
Sheepmaybeanimportantgrassland
managementtool,allowingyouto
achievethecorrectcoversinspring
Globalwarmingmayleadtomoregrassgrowthinwinter.Thensheep
mayhelpmanagewintergrass.
Prepare or Turnout
Field covers at turnout
In the ideal situation all grazing felds would be
at dierent cover levels when you start grazing.
Whencowshavenishedgrazingoneeld,
ideallythenexttobegrazedwillhavejustreached
2800kgDM/ha,soitisreadyforgrazing.
Thisenablesaconstantsupplyofgrassavailable
atthecorrectstagenutritionallyforthecowandfor
maximumphysiologicaloutputforthegrasscrop.
ForexampleseeFig 5.1a(on pages 5-7)
Creatingthedifferentlevelsofcoverrequiredineach
eldformswhatisknownasagrasswedge.Aspring
grasswedgeisparticularlyimportantforspringblock
calvingherdsonalowconcentrateinputsystem.
To set up a grass wedge or spring:
Beginplanninginthepreviousautumn,while
cowsarestillgrazing
Shutupsomeeldsearlyintheautumntoallowgoodlevelsofcovertobecarriedover
tospring
Grazeothereldslaterintoautumn
Considertheslowbutcontinuinggrassgrowth
ratesoverwinter.
Fieldsshutuprstinautumnbecometherst
grazingeldsinspringandthelaterautumngrazed
eldsfallinbehind(see Figure 5.1a feld 1).
When there is no grass wedge
Ifallgrassislefttogrowto2800kgDM/habefore
turnout,therstfeweldswillbeatthecorrectcover.
Butbythetimecowsgettotheremainingeldstheywillhavegrownbeyondtheoptimumforgrazingwith
toomuchcover.
When grass growth is beyond the optimum or grazing:
Grasswillbereducinginquality
Cowswillndthisdifculttograzedownto
theoptimumresidualof1500kgDM/ha
Leavingalongresidualmeanssubsequent
regrowthwillbelowerinqualityandyield Itwillbedifculttogaincontrolandestablish
agrazingwedge.
When turnout may be delayed
Groundconditionsorthecowmanagementsystem
maypreventearlyspringgrazingandinsuch
conditionsalleldsshouldbegrazedrightdownin
autumn/winterwithdrycows,youngstockorsheep
toavoidcoversinexcessof2800kgDM/haatturnout.Thenatturnoutallgrazingeldsmaybeat
similarcovers,givingasimilarscenariotothatseen
aftersilaging.
This can be avoided by:
Onlyletgrassgrowto2200kgDM/haandthen
startinggrazing.Therstfeweldswillbebelowthe
optimumforgrazingbutasgrasscontinuesgrowing
onungrazedelds,coverswillgraduallyincrease
untilcowsaregrazingat2800kgDM/ha.Thiswillestablishawedgeforthesecondgrazinground.
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Asageneralprinciple,introducegrazingslowlyso
therumenhasachancetoadapt.Startwith5kg
DMofgrazedgrassandtheremainderofintakefromthewinterdietandincreasegrazingintakes
overtimetoallowtherumenbugstoadapt.
Theadvantageofthisisthatiftheweatherchanges,
cowscangobackontowinterdietwithoutany
problem,havingtakenadvantageofthecheapest
forageandhavingstartedtosetupagrasswedge
forthecomingseason.
The frst essential or successat the start o the season isto achieve a good arm grasscover at turnout (Section 4).
Thisensuresthecowshaveaccesstosufcient
goodqualitygrazingfromtheoutset.
Ahead o turnout it is also important to: Decidewhicheldstograzerst(Section 4)
Ensurefences,gates,roadways,tracks,water
troughsandpipesareingoodcondition
Checkelectricfencingisworkingwell
Isthegatewaythelimitingfactor
usemultiple-entryslipgates.
Fields that are to be cut or silage cansaely be grazed until mid-April.
Case study
Grazing silage grounds early in the season
Forthelastnineyears,AndrewStevenshasbeen
grazinghissilageeldsearlyintheseasonbefore
shuttingthemupforsilage.
Andrewruns316autumncalversyielding7040
litresat4.19%fatand3.45%protein(totalsolids
of555kg),nearLechladeinGloucestershire,
withalargeemphasisongrazing.
Grazing silage felds allows:
Anearlyturnout
Grasstobesubstitutedforconcentrate
Reductioninfeedcostswithout
anymilkyieldloss
Savingsonwinterhousingcosts.
How does he do this?
Paddockstobegrazedearlyinspringareshut
upinOctoberwithareasonablecover.Andrew
reckonsheachievesthebestresultswhenhetakes
agoodamountofgrassoverwinter,asthengrass
canstarttogrowwellstraightawayaftergrazing.
Good grass cover over winter:
Stimulatesagoodrootstructure
Providesgrassforanearlyturnout
Allowsgrazedgrasstotakeonnutrientsandmoisturequicklyandeffectivelyaftergrazing.
Theaimistostartgrazingbyabout20February.
Andrewmayputon25kgofN/hainFebruary,if
hethinksitsnecessary.
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Eachpaddockisonlygrazedonce,withcows
allocatedenougheachdaysotheygrazedown
toaresidualof1500kgDM/ha.
WithAndrewsset-up,thismeanseachpaddock
isdividedintothreebyastrandofelectric
fencingandcowsgetathirdforeachgrazing.
Thisalsoeliminatesanyregrazingofregrowth,
whichhasaseriousnegativeeffectonthe
regrowthandsubsequentyieldofsilage.
In2007,Andrewwasabletograze19haofhis
24haofsilageground.Thisareaisdictatedby
theweather.Heonlygrazeswhentheconditionsareideal,lookingattheforecast,walkingthe
eldsandplanninggrazing,asanydamagewill
increasethecostofeverytonneofdrymatter.
Whengrazingsilageground,the300cowsare
allocated0.8hato1.2haatatime,depending
ongrassavailability,toachieveagoodresidual
(cowsareabout500-550kgliveweight).
CowsaretakenoffsilagegroundsinthersthalfofMarchandthenprogressaroundthe
grazingarea.Oncecowscomeoffsilage
ground,itreceives125-140kgN/haand75kg
ofpotash/ha,ashisgroundispotashhungry.
Sheepwereonceusedinwinterbuthavenow
beenreplacedbycowsgrazingaslongas
possibleintheautumn,generallyintoDecember
andanearlystarttograzinginspring.
A typical analysis o silage rom groundgrazed until early March shows:
Dry matter 27%Crude protein 13.9%D-value 73ME 11.7MJ/kg pH 3.8NH3 4.5Sugars 1.3
Cowsarefed2/3maizesilage,1/3grasssilage
overwinteruntilturnoutwhengrazingreplaces
grasssilage.
Muck contamination o silage is not a problem when:
Inawellgrazedrotationalsystemthegrassisat
amaximumof2800-3000kgDM/haatentry
andgrazedto1500kgDM/ha,somuckmakes
contactwiththesoilandsoilmicrobesareable
todisperseit
Muckisreasonablyloosebecauseofthegrass
elementofthediet,whichaidsdispersal
Itisdispersedbyrooksseekingoutbugsand
anyundigestedmaizeinmuck.
Thephotographsbelowshowtheswardanditsbase,
demonstratingnoevidenceofmucktocontaminate
silage.Moreimportantly,thebaseisallfreshnew
growthgrowninspring,soitdoesnotcontainany
deadordyingleaforstemmaterialwhichwillreduce
silagequality.
Sward base (taken 3.5.07)
Oncesilagingstarts,cuttingheightisstandardand
notraisedbecauseoffearofmuckcontamination,
asthereisnomuck.
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Thisgroundwascuton23Mayandpicked
upon24May.Andrewnormallyexpectsto
cutbetweenthe20and25Mayandwouldnormallyexpect27to28tonnes/hafreshweight.
Thegrassisalateperennialryegrassley.
Thephotobelowshowsstubblepost-silagingtaken
on25May2007,thedayaftergrasswaslifted.
Ascanbeseenfromthesephotographs,themowerwassetatanormalheightandthereislittleevidence
ofmuckfromthepreviousgrazing,despitean
extremelydryApril.Theverysmallamountofmuck
leftisnotenoughtocontaminatesilageandina
normalAprilwhenthereisraintherewouldbeno
muckleft.
Andrewshowsthatthispracticeispossibleand
successfulintermsofcowhealth,nutrition,grass
utilisation,performanceandmostimportantlyofall
businessefciencyusingresourcestothefull.
DairyCo research suggests that turningcows onto a new pasture in theaternoon could increase milk outputby over 32p/cow/day (Table 5.1).
Becausesugarsareattheirhighestlevelsingrass
andtheirbalancewithNisoptimalintheafternoon,
intakesinthersthourofgrazinghavebeenshowntoincreasebyover15%.
Thereislittleeffectonoverallforageintakebuta
switchtonewpastureintheafternoonhasthe
potentialtoraisedailymilkproductionbyover5%
asaresult.
Table 5.1: Timing o New Forage Allocation
Time oAllocation
Value o
Improvement*(p)
AM PM
Forageintake
rateinrsthour
(gDM/min)
46.6 54.4
Forageintake/
day(kg)17.8 18.0
Milkyield**(litres/day)
21.8 23.1 32.4
* Assumes milk is worth 24.9p/l **Measured over last our weekso a 10-week study
Source: DairyCo Report 96/R3/06: The efcient use o grazedherbage by dairy cows (updated with 2008 fgures).
Turnout Tips Cowsshouldhaveanedgetotheirappetite
Thisedgeofappetitemaybeachievedbycows
runningoutoffeeduptotwohoursbeforethe
morningmilking
Grazethecowsforalimitedperiodinitially
(egthreehours)thenincreasegradually
Agoodleafyswardwillencourageintake
Startgrazingclosetotheyardwhereverpossible.
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Rotation length
Grazingshouldstartin the spring whentheeldcoverreaches2100-2400kgDM/ha(Section 4).
Inthemainseasongrazingshouldstartineach
eldwhenthetargetpre-grazingpointisreached
(Section 3).
Pre-graze Target:
Fieldcoveris2600-3000kgDM/ha
Ryegrasshasatleasttwoandahal, preerably three, leaves.
Cowsshouldberemovedfromaeldwhenthesward
reachesthetargetpost-grazingpoint(Section 3).
Post-graze Target:
Fieldcoveris1500kgDM/ha
Aswardheightof4-5cmwithonequarter to one third o the areacovered in clumps no higher than8-10cm.
Theaimingrazingeachareamustbetoprovidean
allocationofgrassthatallowsthecowstoachieve
maximumintakewithoutgoingbeyondthepost-graze
targetandreducingsubsequentswardproductivity.
Throughouttheseasonitisimportanttoensurethere
isenoughswardinfrontofthecowsbutnotsomuch
thatitiswastedthroughreducedqualityorutilisation.
Thersteldisre-grazedoncetheotheravailableeldshavebeengrazedthetrickbeingtoensure
thatitreachesthepre-grazetargetatexactlythistime.
The key to ensuring this is to adjustthe length o the rotation betweengrazings to accommodate changingsward growth rates.
Using Field Cover Estimates
Individualeldcovermeasurementsmadewitha
risingplatemeter(Section 3)provideagoodwayofestimatinggrazingrotationlengths(Example 5.1).
Measurementsshouldbemadeforalleldsinthe
rotation,weeklyintheseason,tocaterforchanging
swardgrowthrates.
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Example 5.1: Calculating RotationLength with Field Cover
FieldName orNumberand Area*
EstimatedFieldCover
SwardGrowth
Rate **(kgDM/ha)
Days toReachTargetCover
***(2800kgDM/ha)
A B(2800 -A) B
Mid-June
14.1ha 1700 90 12.2
22.8ha 1900 90 10.0
Average 11.1
MidJuly
14.1ha 1700 50 22.0
22.8ha 1900 50 18.0
Average 20.0
* Calculations should be carried out or all felds availableor grazing
** Sward growth rates should be obtained rom individual armsward growth curves (Worksheet 2) or typical fgures (Section 4;Figure 4.2).
*** Target feld cover or the start o grazing should be 2800kgDM/ha.
Thelengthofgrazingrotationcanbeexible
dependinguponthecircumstances.Rotational
grazingallowscontrolovertheareaallocated
forgrazingeachdayandthisabilitytoallocategrazingisanimportantpartofintensive
grazingmanagement.
The key eects rotation length has are:
Controllingtheareaandamountofgrazingthat
cowsareallocatedand,therefore,theirintakeofgrass
Controllingthetimeperiodbetweensuccessive
grazings,sograsshasenoughtimetoregrow
andallowallocationofgrassattheoptimum
growthstagetomaximiseitsfeedqualityand
quantity.(Holmesetal2003).
TheseareillustratedinTable1,Factsheet15.
Reducing the area grazed each day increases rotationlength and has three main eects:
Grassofferedandeateneachdayisreduced,
atleastintheshort-term,whichcanbeuseful
whenthereisagrassshortage
Paddockshavealongerregrowthperiod.This
canbeusefulwhengrowthrateisslow
Grazingintensityisincreased,solessavailable
grassiswasted.Thiscanbeinuencedby
supplementaryfeed.
Thegrazingofferedeachdayshouldbebasedon
theanimalfeedintakeneededandpre-grazingcover.
Therefore,rotationlengthisabalanceofshort-and
medium-termfeedmanagementdecisions.This
explainswhymanyfarmsuserotationsof20to30
daysinspringandnearer100daysinwinter.
(Holmesetal2003).
Worksheet 6 provides a pro ormaor estimating rotation lengths romfeld covers.
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Allocating Swards
Sincerotationlengthsmayneedtochangequitemarkedlyovertheseasonthechangesshouldbe
madegraduallyonanalmostcontinuousbasisto
caterforchangingswardgrowthratesidentied
throughregularmonitoring.
Havingdeterminedthebestrotationlength,sward
allocationscanbemadeonthebasisofcownumbers
andintakes(Example 5.2).
Example 5.2: Sward Allocation
Demand: 150cowsproducing25litres/dayfromspring/earlysummergrazingrequire150x18kg
DM/day(Section 4; Table 4.5 & Example 4.6)=2700kgDM/day.
Supply:Eachhectareoffers2800kgDMattheoutsetandisgrazeddownto1500kgDMproviding
1300kgDMpergrazing.
Area:Thearearequiredtomeetthedailydemandis27001300=2.1ha.Witharotationlengthof
24daysthetotalarearequiredis2.1x24=50.4ha.
Astherateofswardgrowthslowsdowninthesummer
months,pastureswillrequirelongertore-growtothe
target2800kgDM/hapre-grazeeldcover.
Toaccommodatethis,therotationlengthwillneed
tobeextendedbybringingmoreeldsintothe
grazingcycle.
Alternatively,ashortfallinavailablecoverwillarise
andsupplementationmaybenecessary(Section 6).
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Shortalls and surpluses
Grazing shortalls invariably costmoney in lower perormance and/or increased supplementary eeding.
Grazing surpluses also cost money,
primarily in wasting high quality grass.
Monitoringeldcoverovertheseasonallowslikely
imbalancesingrazingsupplyanddemandtobe
cateredforaheadoftime.
AveragefarmcoversfallingfromtheendofApriland
duringtheperiodMayearlySeptembergenerally
indicateashortfallislikely.
Ontheotherhand,increasingaveragefarmcovers
generallyindicateasurplus,particularlyiftheyare
greaterthan2800kgDM/ha.
Assessing Field CoverAvailability (Feed wedge)
Regularplottingoftheindividualcoversofallelds
intherotationonagraphenablespotentialsurplusesorshortfallsinforagesupplyinthenearfutureto
beidentiedbytheshapeofthecurveproduced.
Agraduallyincreasingstraightlineindicatesgood
coveravailabilityintheshort-term(Figure 5.1a).
Arelativelyatorconvex-shapedcurvewith
generallyhighvaluessuggestsashort-term
surplus(Figure 5.1b).
Aushapedorconcavecurvewithanumberof
relativelowvaluesindicatesaloomingshortfall
(Figure 5.1c).
Assessing Pasture Balances
Calculatingpasturegrowth:demandbalances
(Section 4)isanotherusefulwayofidentifyingpotentialgrazingsurplusesorshortfalls
duringtheseason(Example 5.3).
Example 5.3: Pasture Growth:Demand
Balances (Section 4: Example 4.6)
Demand: 150cowsproducing25litres/dayfromspring/earlysummergrazingrequire:
150x18kgDM/day=2700kgDM/day.
Growth: 30haofpastureproducing80kgDM/ha/dayis30x80=2400kgDM/day.
A shortall o pasture is likely to occur here asgrowth is not meeting demand. Action is needed igrowth appears to be continuing at this level.
Growth:30haofpastureproducing120kgDM/ha/dayis30x120=3600kgDM/day.
Pasture growth is well in excess o demand here anda surplus o grazing is looming. Action is needed igrowth appears to be continuing at this level.
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Figure 5.1: Field Cover AvailabilityChart (Feed wedge)
(a) Ideal Situation
3500
3000
2500
2000
1500
1000
500
0
kg/DM/ha
Field number
1 2 3 4 5 6 7 8 9 10 11 12 TargetAverage
FarmCover
AverageFarmCover
(b) Surplus Looming
3500
3000
2500
2000
1500
1000
500
0
kg/DM/ha
Field number
1 2 3 4 5 6 7 8 9 10 11 12 AverageFarmCover
TargetAverage
FarmCover
(c) Shortall Looming
3500
3000
2500
2000
1500
1000
500
0
kg/DM/ha
Field number
1 2 3 4 5 6 7 8 9 10 11 12 AverageFarmCover
TargetAverage
FarmCover
Worksheet 7 provides a proorma or plotting feld coveravailability charts (Feed wedge).
Addressing Sward Surpluses
Grazingeldcoversinexcessof3000kgDM/haresultinlowerpastureproductivityandquality
(Section 3).
Grazing covers greater than 3000kgDM/ha may reduce milk production.
Whenswardslooklikebeingor,arealreadyin
surplusthereareanumberofactionsthatcanbetakentoredressthesituation.
Short-term Actions Closesomeeldsandcutthemforsilage
Thisisagrasslandmanagementstrategyandas
suchtakingasmallamountofsilagemaycost
morethanthemainsilageoperationpertonne
ofsilagemade,butitwillpayintermsoffuture
grazingquality.Itmaybeeasiertobaleand
wrapasmallarea,ratherthanopenaclamp.Resultingbalescaneasilybefedbackinatime
ofdecit.Ifasurplusoccursintherunuptothe
mainsilagetimeitcanbetakenwiththemaincut
Topping,usingamowerearlyintheseason,
mayreducere-growthinthefollowing
rotationbutwillhelptomaintainquality.
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Longer-term Actions Increasethestockingdensityearlierin
theseason
Increasethetotalnumberofstockcarried
Reducetheareainthegrazingrotation
Reducefertiliser/slurry/manureuse
Turnoutearlier/stayoutlater
Carrylesspastureoverwinter,ifatall.Forawet
farm,itmaybeworthwhiletakingcoverright
downintheautumnwithstock,usinglow-yielding
cows,drycows,heifersorsheep,sothatgrassdoesnotgobeyondagoodentrycoverof
2800kgDM/haatturnout.Butthismayleaveall
grazinglandatthesamelevelofcoverwhichwill
requirecarefulmanagement(see page 5-3)
Feedlesssupplementsatgrass
Considerchangingthecalvingpatterninsome
oralloftheherdtobettermatchswardpotential.
Factsheet 13 sets out a simple systemor planning supplementary eedingat grass.
Addressing Sward Shortalls
Grazingswardstolessthan1500kgDM/haor
below4-5cminheightcompromisespasture
productivityandquality(Section 3).
Grazing shortages seriously limit the
ability to produce milk rom grass,increasing production costs markedly.
Whengrazingisinshortsupply,orlookslikeitcould
besoon,thereareanumberofactionsthatcanbe
takentoredressthesituation.
Short-term Actions Increasetheareainthegrazingrotation,
ifpossible
Introduceaforagebufferfeed(Section 6)
Avoidcontinuingtoruncoverdown,
compromisingre-growthsaswellascowfeeding
Considerdrying-offthelowestyieldingcows.
Longer-term Actions Grazesilagegroundbeforeclosing
Builduphighercoversgoingintowinter
Increaseearlyfertiliserapplications
Growlucerne,stubbleturnipsorforagepeas
foradditionalsummerfeeding
Growforagerape,kaleorfodderbeetfor
autumnandearlywinterfeeding
Includewholecropcerealsintherotationfor
useasabufferfeed
Plantobuysupplementslikebrewersgrainsorpressedpulpwhentheyarefavourablypriced
Considerchangingthecalvingpatterninsome
oralloftheherdtobettermatchswardpotential
Considerrenewingolderpastureswithhigher
outputryegrass/clovermixtures(Section 12).
7/29/2019 Grass Programme Sec 5
15/195:15Improvement through grassland management
Feeds per feld
Havingestablishedthegrazingrotationanddaily
swardallocationrequired,thenalcalculation
thatneedstobemadeingrazingmanagementis
thenumberoffeedseacheldorgrazingarea
willprovide.
The primary aim should be to provideaccess to new grazing each eed, withcows spending a maximum o oneday on the same pasture (Section 4).
Calculating Feeds per Field
Eacheldinthegrazingrotationshouldbeassessed
forthenumberoffeedsitwillprovide(Example 5.5).
Thefeedsprovidedwillnotalwaysbeawhole
number.Sofractionsofafeedneedtobeadjusted
upwardsordownwards.
Thisshouldgenerallybedonetothenearesthalf-feed
ontheassumptionthatcowsshouldbemovedafter
eachtwice-dailymilking.
Three-times-a-daymilking,ofcourse,allowsfeed
numberstoberoundedtothenearestthird.
The decision to round up or down should depend on:
Field cover highcoverround-upnumberoffeeds;lesscover
rounddown
Sward quality highqualityround-upnumberoffeeds;poorer
qualityrounddown
Thenumberofupwardanddownwardadjustmentsneedstobethesameiftherotationlengthisto
bemaintained.
Moving cows to new pasture atereach milking is a good way omaximising orage intake, particularlyas the season progresses.
7/29/2019 Grass Programme Sec 5
16/195:16 Improvement through grassland management
Pasture utilisation
Assessingtheactualforagesuppliedbygrazingat
intervalsduringthegrazingseasonprovidesa
valuablecross-checkonlevelsofmilkproduction
actuallybeingachievedfromgrassaswellasactual
pastureofferings.
Italsoallowstheefciencyofswardutilisationto
becalculated(Section 2).
Sward Utilisation Target: 70-80%.
Wheregoodqualityswardsaregrazedclose
totheidealpost-grazingpointutilisation
valuesmaybehigherthan80%.
Swardutilisationtargetsofcloserto100%are
notadvisableasanimalintakesarelikelytobe
compromisedatthisefciencyofpastureuse.
Swardutilisationsgreaterthan100%
indicateswardsarebeingovergrazedand
subsequentre-growthwillbecompromised.
For most purposes a simple DMcalculation will be quite sufcient toassess and monitor utilisation efciency.
Similarcalculationscanbecarriedoutto
establishtheefciencyofMEutilisation.
Theresultismoreaccurateasittakesaccountof
thestageoflactationofthecowbutitisoverly
complicatedforpracticalday-to-dayuse.
Example 5.4: Calculating Field Feed Numbers
Total GrazingArea (ha)
AverageRotation
Length (days)
Average DailyAllocation (ha)
Size o EachField (ha)
Numbero Feeds inEach Field
(Calculated)
Number oFeeds in Each
Field (Adjusted)
A B C(AB) D (DC)
56 20 2.8 5 1.8 2
6 2.1 27 2.5 2.5
8 2.9 3
Etc.......
Worksheet 8 provides a pro ormaor calculating eeds per feld.
7/29/2019 Grass Programme Sec 5
17/195:17Improvement through grassland management
Calculating Sward Intake
Swardintakeiseasytocalculatefromtheinformationalreadyrecorded(Example 5.5).
Example 5.5: Sward Intake
Total
Grazing
Area(ha)
Rotation
Length
(days)
Daily
Allocation
(ha)
Pre-graze
Field
Cover(kg
DM/ha)
Post-graze
Field
Cover(kg
DM/ha)
Field Cover
Allocated
(kg DM/ha)
Total
Pasture
Oered (kg
DM/day)
Milking
Cow
Numbers*
Individual
Pasture
Oered
(kg DM/
cow/day)
A B C =(A B)
D E F =(D E)
G =(C x F)
H (G H)
45 19 2.4 2800 1500 1300 3120 180 17.3
* High-yielding cows (over 15 litres/day) only. I necessary do a separate calculation or the lower yielding group.
Worksheet 9 provides a pro orma orcalculating sward intake.
Measuring Sward Utilisation
Swardutilisationcanbestbemeasuredbyassessing
theactualintakeofswardDMcomparedtothecover
allocated(Example 5.6).
Swardintakeisestimatedeitherbycalculation
(Example 5.5)orbydifferencefromtheintakeofallotherfeedsandthepredictedDMintakeofthecow.
Example 5.6: Estimating Sward Utilisation Efciency
Cover Allocation: 1500kgDM/dayisprovidedtoaherdof
100cows,givinganindividualallocation
of1500100=15kgDM/head/day.
Sward Intake: Cowsweighing600kghaveaDMintake
of18kgandareconsuming6kgDMas
cakeintheparlour,givinganintakefrom
grazingof18-6=12kg/head/day.
Sward Utilisation: Theefciencyofutilisationistheactualintakedivided
bytheallocation:1215kg=0.8(or80%).
Factsheet 14 provides advice onrearing heiers at grass.
7/29/2019 Grass Programme Sec 5
18/195:18 Improvement through grassland management
ThepredictedDMintakeofthecowisapproximately
equivalentto3%ofbodyweightforcows
weighing550,600or700kgthismeans16.5kg,18kgand21kgrespectively(swardDMintake
beyond18-19kgDMisnotgenerallypossible).
Getting Grazing Back Under Control
Thisgenerallyreferstonotachievingthecorrect
residualcoverof1500kgDM/ha.Mistakeswill
happenanditisnotalwayspossibletograzeto
1500kgDM/ha.Forexample,cowsarelesslikelyto
achievetheresidualonareallywetday,butitisimportanttocorrectthepoorresidualleftbycowsso
futurequalityisnotlost.Onewaytomonitorresiduals
istoscoreeacheldwhencowscomeout.For
exampleonascaleof1-5,with1beinggoodand5
poor,makeanoteofthisinadiary,allowingactionto
betakenoneldswithascoreof1,2andpossibly3.
There are a number o ways to correct a poor residual:
Considerwhethertoomuchwasallocated.Ifthis
isso,thentryreducingtheallocationandseewhethercowsgrazeharder(sometrough-fed
cowsdoneedabitoftraining)
Ifthereisnottoomuchleft,goinimmediately
behindthecowsandtopthearea.Amoweris
best,asitmakesacleanercutanddoesnot
tendtopushgrassdownlikeatopper.The
mowerwillcuttoabout1500kgDM/ha,
restoringagoodresidual.Donotdothisif
thereisamassofgrassasmowedmaterial
willshadeoutnewgrowth Mowgrass12to24hoursbeforegrazing.
Thisisparticularlyusefullaterintheseason
whenseedheadsareappearing,butitdoes
requiredryweather.Useamowerandwilt
grassforupto24hours.Experiencefrom
aroundthecountryshowsthisworkswell
(however,ithasbeensuggesteditdoesnot
workwellwithJerseys)
Photo 13 below shows a feld ready or cows tograze ater mowing and wilting. Photo 14 shows
another feld which has been mowed, wilted andgrazed. This photo was taken a ew days atergrazing and good regrowth has been achieved.
Photo 13 Grass mowed and wilted pre-grazing.Courtesy o Will Edwards
Photo 14 Regrowth ater mowing, wilting and grazing.
Courtesy o Will Edwards Regrowtheareawithapoorresidualfora
weekorsountilthereisafreshswardandthen
grazewithotherstock,suchasheifersandmake
themgrazeithardtoachievea1500kgDM/
haresidualthenallowtoregrowto2800kg
DM/haandre-enterthegrazingrotation
Designatetheareatobesilagedinthenextround.
Themowerwillthenreinstateagoodresidual.
Thesestrategiesarenotanexcuseforpoorgrazingmanagement,asthecheapestwaytogetthe
optimumswardregrowthisforcowstograzedown
to1500kgDM/ha.However,mosteldsmayneed
oneoftheabovetechniquesinthegrazingseason.
Ifacertaineldorpartthereofconsistentlyhasa
poorresidual,itmaybeapalatabilityissueanditis
worthconsideringgrasstypes,soilpH,soilindices,
(P,Kandotherelements)previouseldhistory(such
asexcessivedirtywaterand/orslurryapplications).
Grassvarietiesalsohavedifferingpalatability.
7/29/2019 Grass Programme Sec 5
19/19
Summary TheidealPre-grazePointiswhenryegrass
reacheseldcoverof2800-3000kgDM/ha
Grazingshouldcontinueuntiltheswardis
4-5cmhigh(withonequartertoonethird
oftheareacoveredinclumpsnohigher
than8-10cm)oreldcoverreaches
1500kgDM/ha
Grazingrotationlengthcanbestbe
monitoredandadjustedthroughouttheseasonusingeldcovermeasurements
Monitoringeldcoverandaveragefarm
coveronaregularbasisallowspotential
grazingsurplusesorshortfallstobeidentied
andaddressedbeforetheycreateproblems
Carefulallocationoffeedspereldonthe
basisofareaandrotationlengthwillensure
themostefcientutilisationofpasture
Targetswardutilisationefciencyshould
be70-80%.
Section 2: CalculatingtheCostofYourFeeds
Section 3: AssessingYourPasture
Section 4: PlanningYourGrazing
Section 6: SupplementingGrazing
Section 12: RenewingSwardsSection 14: GrazingHigh-yieldingCows
Section 15: Factsheet13:TheCrichtonSTARSystemFactsheet14:RearingHeifersatGrass
Section 16: Worksheet5:RotationLength (Three-leafAssessment)
Worksheet6:RotationLength
(FieldCoverAssessment)
Worksheet7:FieldCoverAvailability
Worksheet8:FeedsperField
Worksheet9:SwardIntake
Seealso...
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